[Intersection Observer - After scroll to block - do something] Intersection Observer - After scroll to block - do something

main.js

        const observer = new IntersectionObserver(handleIntersection, { threshold: 0 });

        function handleIntersection(entries, observer) {
            entries.forEach(entry => {
                if (entry.isIntersecting) {
                    entry.target.style.backgroundColor = "#e74c3c";
                } else {
                    entry.target.style.backgroundColor = "#3498db";
                }
            });
        }

        const wrappers = document.querySelectorAll(".wrapper");
        wrappers.forEach((entry) => { observer.observe(entry) });